Transcript Geology and Minerals

Core Case Study: The Real Cost of Gold
• Gold producers
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China
South Africa
Australia
United States
Canada
• Cyanide heap leaching
• Extremely toxic to birds and mammals
• Spills contaminate drinking water and kill birds and fish
Gold Mine with Cyanide Leach Piles and
Ponds in South Dakota, U.S.
Fig. 14-1, p. 346
What Are the Earth’s Major Geological
Processes and Hazards?
• Dynamic processes move matter within the earth and
on its surface, and can cause volcanic eruptions,
earthquakes, tsunamis, erosion, and landslides.
The Earth Is a Dynamic Planet
• What is geology?
• Dynamic processes taking place on earth’s surface
and in earth’s interior
• Three major concentric zones of the earth
• Core
• Mantle
• Including the asthenosphere
• Crust
• Continental crust
• Oceanic crust: 71% of crust
Major Features of the Earth’s Crust and
Upper Mantle
Fig. 14-2, p. 348
The Earth Beneath Your Feet Is
Moving
• Convection cells, or currents
• Tectonic Plates
• Lithosphere
The Earth Beneath Your Feet Is
Moving
• Three types of boundaries between plates
• Divergent boundaries
• Magma
• Oceanic ridge
• Convergent boundaries
• Subduction zone
• Trench
• Transform boundaries: San Andreas fault
The Earth’s Crust Is Made Up of a Mosaic of Huge
Rigid Plates: Tectonic Plates
Fig. 14-3, p. 348
The Earth’s Major Tectonic Plates
Fig. 14-4, p. 349
The San Andreas Fault as It Crosses Part of the Carrizo
Plain in California, U.S.
Fig. 14-5, p. 350
Some Parts of the Earth’s Surface Build Up
and Some Wear Down
• Internal geologic processes
• Generally build up the earth’s surface
• External geologic processes
• Weathering
• Physical, chemical, and biological
• Erosion
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Wind
Flowing water
Human activities
Glaciers
Volcanoes Release Molten Rock from
the Earth’s Interior
• Volcano
• Fissure
• Magma
• Lava
• 1991: Eruption of Mount Pinatubo
• Benefits of volcanic activity
Creation of a Volcano
Fig. 14-6, p. 351
Earthquakes Are Geological Rock-and-Roll
Events
• Earthquake
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Seismic waves
Focus
Epicenter
Magnitude
Amplitude
Earthquakes Are Geological Rock-and-Roll
Events
• Richter scale
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Insignificant: <4.0
Minor: 4.0–4.9
Damaging: 5.0–5.9
Destructive: 6.0–6.9
Major: 7.0–7.9
Great: >8.0
• Largest recorded earthquake: 9.5 in Chile in 1960
Major Features and Effects of an
Earthquake
Fig. 14-7, p. 351
Liquefaction of recent
sediments causes buildings
to sink
Landslides may
occur on hilly
ground
Two adjoining plates
move laterally along the
fault line
Earth movements
cause flooding in
low-lying areas
Shock waves
Epicenter
Focus
Fig. 14-7a, p. 351
Earthquake Risk in the United States
Figure 16, Supplement 8
World Earthquake Risk
Figure 17, Supplement 8
Earthquakes on the Ocean Floor Can Cause
Huge Waves Called Tsunamis
• Tsunami, tidal wave
• Travels several hundred miles per hour
• Detection of tsunamis
• Buoys in open ocean
• December 2004: Indian Ocean tsunami
• Magnitude 9.15 and 31-meter waves at shore
• Role of coral reefs and mangrove forests in reducing
death toll
Formation of a Tsunami and Map of Affected
Area of Dec 2004 Tsunami
Fig. 14-8, p. 352
Shore near Gleebruk in Indonesia before and
after the Tsunami on June 23, 2004
Fig. 14-9, p. 353
How Are the Earth’s Rocks Recycled?
• The three major types of rocks found in the earth’s
crust—sedimentary, igneous, and metamorphic—are
recycled very slowly by the process of erosion,
melting, and metamorphism.
There Are Three Major Types of Rocks
• Minerals
• Element or inorganic compound in earth’s crust
• Usually a crystalline solid
• Regular and repeating arrangement of atoms
• Rock
• Combination of one or more minerals
There Are Three Major Types of Rocks
1. Sedimentary
• Sediments from eroded rocks or plant/animal remains
• Transported by water, wind, gravity
• Deposited in layers and compacted
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Sandstone
Shale
Dolomite
Limestone
Lignite
Bituminous coal
There Are Three Major Types of Rocks
2. Igneous
• Forms below or at earth’s surface from magma
• Granite
• Lava rocks
3. Metamorphic
• Preexisting rock subjected to high pressures, high temperatures,
and/or chemically active fluids
• Anthracite
• Slate
• Marble
The Earth’s Rocks Are Recycled
Very Slowly
• Rock cycle
• Slowest of the earth’s cyclic processes
Natural Capital: The Rock Cycle
Fig. 14-10, p. 354
What Are Mineral Resources, and What
Are their Environmental Effects?
• We can make some minerals in the earth’s crust into
useful products, but extracting and using these
resources can disturb the land, erode soils, produce
large amounts of solid waste, and pollute the air,
water, and soil.
We Use a Variety of Nonrenewable
Mineral Resources
• Mineral resource
• Can be extracted from earth’s crust and processed into raw
materials and products at an affordable cost
• Metallic minerals
• Nonmetallic minerals
• Ore
• Contains profitable concentration of a mineral
• High-grade ore
• Low-grade ore
We Use a Variety of Nonrenewable
Mineral Resources
• Metallic mineral resources
• Aluminum
• Iron for steel
• Copper
• Nonmetallic mineral resources
• Sand, gravel, limestone
• Reserves: estimated supply of a mineral resource
Some Environmental Impacts of Mineral
Use
• Advantages of the processes of mining and
converting minerals into useful products
• Disadvantages
The Life Cycle of a Metal Resource
Fig. 14-11, p. 355
Extracting, Processing, Using Nonrenewable
Mineral and Energy Resources
Fig. 14-12, p. 356
There Are Several Ways to Remove
Mineral Deposits
• Surface mining
• Shallow deposits removed
• Overburden removed first
• Spoils: waste material
• Subsurface mining
• Deep deposits removed
There Are Several Ways to Remove
Mineral Deposits
• Type of surface mining used depends on
• Resource
• Local topography
• Types of surface mining
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Open-pit mining
Strip mining
Contour strip mining
Mountaintop removal
Natural Capital Degradation: Open-Pit Mine in
Arizona
Fig. 14-13, p. 357
Area Strip Mining in Wyoming
Fig. 14-14, p. 357
Natural Capital Degradation: Contour Strip
Mining
Fig. 14-15, p. 358
Mining Has Harmful Environmental Effects
• Scarring and disruption of the land surface
• E.g., spoils banks
• Mountain top removal for coal
• Loss of rivers and streams
• Air pollution
• Groundwater disruption
• Biodiversity decreased
Mining Has Harmful Environmental Effects
• Subsurface mining
• Subsidence
• Acid mine drainage
• Major pollution of water and air
• Effect on aquatic life
• Large amounts of solid waste
Spoils Banks in Germany from Area Strip
Mining
Fig. 14-16, p. 358
Mountaintop Coal Mining in West Virginia
Fig. 14-17, p. 359
Ecological Restoration of a Mining Site in
Indonesia
Fig. 14-18, p. 360
Removing Metals from Ores Has Harmful
Environmental Effects
• Ore extracted by mining
• Ore mineral
• Gangue = waste material
• Smelting using heat or chemicals
• Air pollution
• Water pollution
Removing Metals from Ores Has Harmful
Environmental Effects
• Liquid and solid hazardous wastes produced
• Use of cyanide salt of extract gold from its ore
• Summitville gold mine: Colorado, U.S.
How Long Will Supplies of Nonrenewable
Mineral Resources Last?
• All nonrenewable mineral resources exist in finite
amounts, and as we get closer to depleting any
mineral resource, the environmental impacts of
extracting it generally become more harmful.
• Raising the price of a scarce mineral resource can
lead to an increase in its supply, but there are
environmental limits to this effect.
Mineral Resources Are Distributed
Unevenly
• Most of the nonrenewable mineral resources
supplied by
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United States
Canada
Russia
South Africa
Australia
• Sharp rise in per capita use in the U.S.
Mineral Resources Are Distributed
Unevenly
• Strategic metal resources
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Manganese (Mn)
Cobalt (Co)
Chromium (Cr)
Platinum (Pt)
Supplies of Nonrenewable Mineral Resources
Can Be Economically Depleted
• Future supply depends on
• Actual or potential supply of the mineral
• Rate at which it is used
Supplies of Nonrenewable Mineral Resources
Can Be Economically Depleted
• When it becomes economically depleted
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Recycle or reuse existing supplies
Waste less
Use less
Find a substitute
Do without
• Depletion time: time to use a certain portion of
reserves
Natural Capital Depletion: Depletion Curves for
a Nonrenewable Resource
Fig. 14-19, p. 361
Market Prices Affect Supplies of
Nonrenewable Minerals
• Subsidies and tax breaks to mining companies keep
mineral prices artificially low
• Does this promote economic growth and national
security?
• Scarce investment capital hinders the development
of new supplies of mineral resources
Case Study: The U.S. General Mining
Law of 1872
• Encouraged mineral exploration and mining of hardrock minerals on U.S. public lands
• Developed to encourage settling the West (1800s)
• Until 1995, land could be bought for 1872 prices
• Companies must now pay for clean-up
Colorado Gold Mine Must Be Cleaned up by the
EPA
Fig. 14-20, p. 363
Is Mining Lower-Grade Ores the Answer?
• Factors that limit the mining of lower-grade ores
• Increased cost of mining and processing larger
volumes of ore
• Availability of freshwater
• Environmental impact
• Improve mining technology
• Use microorganisms, in situ
• Slow process
• What about genetic engineering of the microbes?
Can We Extend Supplies by Getting More
Minerals from the Ocean?
• Mineral resources dissolved in the ocean -- low
concentrations
• Deposits of minerals in sediments along the shallow
continental shelf and near shorelines
Can We Extend Supplies by Getting More
Minerals from the Ocean?
• Hydrothermal ore deposits
• Metals from the ocean floor: manganese nodules
• Effect of mining on aquatic life
• Environmental impact
Natural Capital: Hydrothermal Deposits
Fig. 14-21, p. 364
How Can We Use Mineral Resources More
Sustainability?
• We can try to find substitutes for scarce resources,
reduce resource waste, and recycle and reuse
minerals.
We Can Find Substitutes for Some Scarce
Mineral Resources
• Materials revolution
• Nanotechnology
• Ceramics
• High-strength plastics
• Drawbacks?
We Can Find Substitutes for Some Scarce
Mineral Resources
• Substitution is not a cure-all
• Pt: industrial catalyst
• Cr: essential ingredient of stainless steel
Science Focus: The Nanotechnology
Revolution
• Nanotechnology, tiny tech
• Uses
• Nanoparticles
• Are they safe?
• Investigate potential ecological, economic, health, and
societal risks
• Develop guidelines for their use until more is known about
them
We Can Recycle and Reuse
Valuable Metals
• Recycling
• Lower environmental impact than mining and
processing metals from ores
• Reuse
Aluminum Cans Ready for Recycling
Fig. 14-22, p. 366
We Can Use Mineral Resources More
Sustainability
• How can we decrease our use and waste of mineral
resources?
• Pollution and waste prevention programs
Solutions: Sustainable Use of Nonrenewable
Minerals
Fig. 14-23, p. 366
Case Study: Pollution Prevention Pays
• Begun in 1975 by 3M company, a very large
manufacturing company
• Redesigned equipment and processes
• Fewer hazardous chemicals
• Recycled or sold toxic chemical outputs
• Began making nonpolluting products
• Company saved $1.2 billion
• Sparked cleaner production movement
Three Big Ideas
1. Dynamic forces that move matter within the earth
and on its surface recycle the earth’s rocks, form
deposits of mineral resources, and cause volcanic
eruptions, earthquakes, and tsunamis.
2. The available supply of a mineral resource depends
on how much of it is in the earth’s crust, how fast
we use it, mining technology, market prices, and
the harmful environmental effects of removing and
using it.
Three Big Ideas
3. We can use mineral resources more sustainably by
trying to find substitutes for scarce resources,
reducing resource waste, and reusing and recycling
nonrenewable minerals.